PHP, Arrays & Functional Programming
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The document discusses functional programming and array functions in PHP, highlighting the importance of immutability and code readability. It presents various coding examples and performance comparisons between traditional loops and functional approaches like array_map. Additionally, it promotes the use of a custom 'arraywrap' class for enhanced array manipulation and performance.
![4/2016
$idsToLoad = array_diff($idsRequired, $idsLoaded);
// e.g. cities -> countries
$referencedCountryIds = array_unique([1,1,2,3]);
Array Functions](https://image.slidesharecdn.com/slidesharephparraysfunctionalprogramming-2-160422095658/85/PHP-Arrays-Functional-Programming-14-320.jpg)
![4/2016
$array = array_pad([], 10, 0);
foreach ($array as &$item) {
$item = rand();
}
// find max
$max = null;
foreach ($array as $item) {
$max = $max === null ?
$item : max($max, $item);
}](https://image.slidesharecdn.com/slidesharephparraysfunctionalprogramming-2-160422095658/85/PHP-Arrays-Functional-Programming-20-320.jpg)
![4/2016
ArrayWrap::create([])
->pad(10, 0)
->map(function () { return rand(); })
->max();](https://image.slidesharecdn.com/slidesharephparraysfunctionalprogramming-2-160422095658/85/PHP-Arrays-Functional-Programming-21-320.jpg)
![4/2016
// [x] immutable
// [x] no side effects
$emptyArr = ArrayWrap::create([]);
$padded = $emptyArr->pad(10, 0);
$randList = $padded->map( … );
$max = $randList->max();
var_dump($emptyArr === $padded); // false
var_dump($padded === $randList); // false](https://image.slidesharecdn.com/slidesharephparraysfunctionalprogramming-2-160422095658/85/PHP-Arrays-Functional-Programming-22-320.jpg)
![4/2016
$ids = []
foreach ($models as $model) {
$ids[] = $model->id;
}
$ids = array_map(
function ($model) { return $model->id; },
$models
);
Extract a list of ids](https://image.slidesharecdn.com/slidesharephparraysfunctionalprogramming-2-160422095658/85/PHP-Arrays-Functional-Programming-25-320.jpg)
![4/2016
$assigned = [];
foreach ($instances as $instance) {
$assigned[$instance->id] = $instance;
}
$assigned = array_combine(array_map(
function ($instance) {return $instance->id;},
$instances
), $instances);
Assign by id](https://image.slidesharecdn.com/slidesharephparraysfunctionalprogramming-2-160422095658/85/PHP-Arrays-Functional-Programming-27-320.jpg)
![4/2016
$yelled = [‘OH’, ‘SO’, ‘LOUD’];
$pssst = [];
foreach ($yelled as $v) {
$pssst[] = strtolower($v);
}
$pssst = array_map(‘strtolower’, $yelled);
Apply native functions](https://image.slidesharecdn.com/slidesharephparraysfunctionalprogramming-2-160422095658/85/PHP-Arrays-Functional-Programming-29-320.jpg)
PHP, Arrays & Functional Programming
- 1. PHP, Arrays & Functional Programming
- 2. 4/2016 Model Driven Software Development Sclable transforms your knowledge into enterprise-grade, ready-to-go Business Applications. Sclable Business Solutions GmbH https://sclable.com/
- 3. 4/2016 By the way: We’re always looking for Full Stack Developers
- 4. 4/2016 Sclable Platform Senior Developer PL/PGSQL - PHP - JS ← full stack → Aviation Enthusiast Michael Rutz
- 5. 4/2016 f(x) === f(x) Immutable y = x; f(x); x === y; No side effects Functional Programming
- 6. 4/2016 $first = 0; $second = 1; for ($i = 0; $i < 10; $i++) { echo $first . PHP_EOL; $tmp = $first; $first = $second; $second += $tmp; } Functional Programming Global state has changed
- 7. 4/2016 function fibonacci($n, $first = 0, $second = 1) { if ($n === 0) return ''; return $first . PHP_EOL . fibonacci(--$n, $second, $first + $second); } echo fibonacci(10); Functional Programming Global state untouched Immutable
- 9. 4/2016 Imperative design, but Closures ✓ Functional Programming in PHP
- 10. 4/2016 $ids = array_map(function ($item) { return $item->id; }, $list); // js / ES2015 let ids = list.map(item => item.id); Functional Programming in PHP
- 11. 4/2016 Implemented the right way, code readability can be improved. Functional Programming in PHP
- 13. 4/2016 Performance ! Nice shorthands ! Array Functions
- 14. 4/2016 $idsToLoad = array_diff($idsRequired, $idsLoaded); // e.g. cities -> countries $referencedCountryIds = array_unique([1,1,2,3]); Array Functions
- 15. 4/2016 array array_map(callable, array, array...) bool array_walk(&array, callable) array array_unique(array, sort_flags) Inconsistent API
- 16. 4/2016 https://github.com/sclable/array-functions composer require sclable/array-functions class ArrayWrap
- 17. 4/2016 Normalized Params OO & FP Approach class ArrayWrap
- 18. 4/2016 // e.g. cities -> countries $referencedCountryIds = ArrayWrap::create($cities) ->map(function ($city) { return->countryId; }) ->unique(); e.g.
- 19. 4/2016 More e.g.
- 20. 4/2016 $array = array_pad([], 10, 0); foreach ($array as &$item) { $item = rand(); } // find max $max = null; foreach ($array as $item) { $max = $max === null ? $item : max($max, $item); }
- 21. 4/2016 ArrayWrap::create([]) ->pad(10, 0) ->map(function () { return rand(); }) ->max();
- 22. 4/2016 // [x] immutable // [x] no side effects $emptyArr = ArrayWrap::create([]); $padded = $emptyArr->pad(10, 0); $randList = $padded->map( … ); $max = $randList->max(); var_dump($emptyArr === $padded); // false var_dump($padded === $randList); // false
- 23. 4/2016 foreach vs. array_map/array_walk Performance Considerations
- 24. 4/2016 ! major performance impact on closures ! xDebug
- 25. 4/2016 $ids = [] foreach ($models as $model) { $ids[] = $model->id; } $ids = array_map( function ($model) { return $model->id; }, $models ); Extract a list of ids
- 26. 4/2016 Foreach vs. Array_map 1:0 Extract a list of ids
- 27. 4/2016 $assigned = []; foreach ($instances as $instance) { $assigned[$instance->id] = $instance; } $assigned = array_combine(array_map( function ($instance) {return $instance->id;}, $instances ), $instances); Assign by id
- 28. 4/2016 Foreach vs. Array_map 2:0 Assign by id
- 29. 4/2016 $yelled = [‘OH’, ‘SO’, ‘LOUD’]; $pssst = []; foreach ($yelled as $v) { $pssst[] = strtolower($v); } $pssst = array_map(‘strtolower’, $yelled); Apply native functions
- 30. 4/2016 Foreach vs. Array_map 2:1 Apply native functions
- 32. 4/2016 Performance. But readability! Conclusions + It looks cool!
- 33. 4/2016 Thank you. That’s all folks!